The present invention relates to a hand-held pneumatic tube test gun that can be used by an operator to pressure test tubes in heat exchangers.
Tube testing guns have been utilized in the heat exchanger industry. A conventional tube testing gun includes an end carrying a seal which is adapted to be inserted into an open end of a tube. The seal is expanded against the inner diameter of the tube and pressure is introduced in the tube downstream of the seal. Leaks are thereby able to be determined by monitoring pressure decay following pressurization of the tube to a pre-determined test level.
Thus, in use, a conventional tube test gun is connected to a source of compressed air and is partially inserted into one open end of a tube while a separate plugging gun or the like is inserted into an opposite open end of the tube. An air control valve on the test tube gun is manually activated by the operator to inject air into the tube to pressurize the tube. The air injected into the tube may cause or contribute to expansion of seals provided on the inserted portions of the guns into sealing engagement with the inner diameter of the tube and thereafter increase the air pressure within the tube between the seals. When the pressure in the tube stabilizes and reaches a level desired for testing purposes, the air control valve on the gun is deactivated so that air is no longer injected into the tube. Any reduction of pressure within the tube is indicated via a pressure gauge integral with the gun to reveal even the smallest of tube leaks.
The conventional tube test gun is held in place at the tube end by friction created between the expanded seal and the inner diameter of the tube and by the manual force of the operator holding the test gun at the end of the tube. Such a test gun can unintentionally slip out of a pressurized tube. When this occurs, there is a sudden decompression of the tube and release of energy adjacent the holder/operator of the test gun.
A current typical resolution of the above referenced problem and safety issue is to increase the friction force created between the seal and the inner diameter of the tube. This can be provided by using a larger actuation piston within the gun and/or by providing separate valves within the gun, one to energize the seal and a separate one to pressurize the tube. In addition, the operator may be required to exert greater pushing force on the gun throughout the duration of a test.